Abstract
This study examines how the signal-to-noise-interference ratio (SNIR) influences auditory performance and neural responses associated with listening effort (LE). A new dataset was collected from individuals with moderate hearing loss, all fitted with hearing aids (HAs). Participants listened to two competing audiobooks presented via front-facing loudspeakers, while 16-talker babble noise was delivered from background speakers. Six SNIR levels (5.47, - 3.55, - 2.13, - 1.19, - 0.64, and - 0.27 dB) were tested. Participants were instructed to attend to one audiobook while ignoring the competing speech and background noise and were subsequently assessed on content of the attended speech and perceived LE. The performance results revealed a significant linear effect of SNIR on subjective ratings of LE and a primarily quadratic effect on comprehension questionnaire accuracy, suggesting that perceived effort decreases steadily with improving SNIR, while comprehension questionnaire performance exhibits a plateau at higher SNIR levels. The EEG analyses demonstrated a significant relationship between SNIR and local connectivity, specifically in the parietal electrodes and in the alpha frequency band. Further analysis confirmed that parietal local connectivity correlates linearly with subjective LE ratings. Moreover, spectral power analysis showed that parietal alpha power is not significantly related to SNIR, indicating that local connectivity may serve as a more sensitive neural marker. While local connectivity and alpha power may share some neural underpinnings, they offer complementary, yet non-identical insights. These findings highlight the potential of local EEG connectivity as a reliable estimate of LE in acoustically challenging environments.